The wonders of diarrhea

There are four mechanisms of diarrhea:
- malabsorption/ maldigestion

• example: result of selective deficiencies of brush border enzymes such as disaccharidases
• other possible causes: loss of enterocyte function, loss of absorptive surface area, non-intestinal causes
• osmotic diarrhea is typically a small intestine problem in small animals and can occur significantly in the colon of large animals.

- hypersecretion despite structurally intact muscosa

• electrolyte and fluid move into the intestinal lumen
• often associated with entertoxins of intraluminal pathogens, such as the heat stable toxin of E. coli and the virulence factors of Shigella and Salmonella

- exudative (due to direct damage to vessels or increased hydrostatic pressure)

• example 1: direct damage can be caused by Salmonellosis
• example 2: increased hydrostatic pressure can result from Johne's disease

- deranged intestinal motility

• hypomotility (abnormal proliferation of microflora) or hypermotility (reduced contact time)
• can be caused by tumors, foreign bodies, intussusception, strictures, acute inflammation